/**
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.onemile.utils;

import java.io.UnsupportedEncodingException;

import android.R.integer;

/***
 * Utilities for encoding and decoding the UtiBase64 representation of binary
 * data. See RFCs <a href="http://www.ietf.org/rfc/rfc2045.txt">2045</a> and <a
 * href="http://www.ietf.org/rfc/rfc3548.txt">3548</a>.
 */
public class UtiBase64
{
   /***
    * Default values for encoder/decoder flags.
    */
   public static final int DEFAULT = 0;

   /***
    * Encoder flag bit to omit the padding '=' characters at the end of the
    * output (if any).
    */
   public static final int NO_PADDING = 1;

   /***
    * Encoder flag bit to omit all line terminators (i.e., the output will be on
    * one long line).
    */
   public static final int NO_WRAP = 2;

   /***
    * Encoder flag bit to indicate lines should be terminated with a CRLF pair
    * instead of just an LF. Has no effect if {@code NO_WRAP} is specified as
    * well.
    */
   public static final int CRLF = 4;

   /***
    * Encoder/decoder flag bit to indicate using the "URL and filename safe"
    * variant of UtiBase64 (see RFC 3548 section 4) where {@code -} and
    * {@code _} are used in place of {@code +} and {@code /}.
    */
   public static final int URL_SAFE = 8;

   /***
    * Flag to pass to {@link Base64OutputStream} to indicate that it should not
    * close the output stream it is wrapping when it itself is closed.
    */
   public static final int NO_CLOSE = 16;

   // --------------------------------------------------------
   // shared code
   // --------------------------------------------------------

   /** package */
   static abstract class Coder
   {
	  public byte[] output;
	  public int op;

	  /***
	   * Encode/decode another block of input data. this.output is provided by
	   * the caller, and must be big enough to hold all the coded data. On exit,
	   * this.opwill be set to the length of the coded data.
	   * 
	   * @param finish
	   *           true if this is the final call to process for this object.
	   *           Will finalize the coder state and include any final bytes in
	   *           the output.
	   * 
	   * @return true if the input so far is good; false if some error has been
	   *         detected in the input stream..
	   */
	  public abstract boolean process(byte[] input, int offset, int len, boolean finish);

	  /***
	   * @return the maximum number of bytes a call to process() could produce
	   *         for the given number of input bytes. This may be an
	   *         overestimate.
	   */
	  public abstract int maxOutputSize(int len);
   }

   // --------------------------------------------------------
   // decoding
   // --------------------------------------------------------

   /***
    * Decode the UtiBase64-encoded data in input and return the data in a new
    * byte array.
    * 
    * <p>
    * The padding '=' characters at the end are considered optional, but if any
    * are present, there must be the correct number of them.
    * 
    * @param str
    *           the input String to decode, which is converted to bytes using
    *           the default charset
    * @param flags
    *           controls certain features of the decoded output. Pass
    *           {@code DEFAULT} to decode standard UtiBase64.
    * 
    * @throws IllegalArgumentException
    *            if the input contains incorrect padding
    */
   public static byte[] decode(String str, int flags)
   {
	  return decode(str.getBytes(), flags);
   }

   /***
    * Decode the UtiBase64-encoded data in input and return the data in a new
    * byte array.
    * 
    * <p>
    * The padding '=' characters at the end are considered optional, but if any
    * are present, there must be the correct number of them.
    * 
    * @param input
    *           the input array to decode
    * @param flags
    *           controls certain features of the decoded output. Pass
    *           {@code DEFAULT} to decode standard UtiBase64.
    * 
    * @throws IllegalArgumentException
    *            if the input contains incorrect padding
    */
   public static byte[] decode(byte[] input, int flags)
   {
	  return decode(input, 0, input.length, flags);
   }

   /***
    * Decode the UtiBase64-encoded data in input and return the data in a new
    * byte array.
    * 
    * <p>
    * The padding '=' characters at the end are considered optional, but if any
    * are present, there must be the correct number of them.
    * 
    * @param input
    *           the data to decode
    * @param offset
    *           the position within the input array at which to start
    * @param len
    *           the number of bytes of input to decode
    * @param flags
    *           controls certain features of the decoded output. Pass
    *           {@code DEFAULT} to decode standard UtiBase64.
    * 
    * @throws IllegalArgumentException
    *            if the input contains incorrect padding
    */
   public static byte[] decode(byte[] input, int offset, int len, int flags)
   {
	  // Allocate space for the most data the input could represent.
	  // (It could contain less if it contains whitespace, etc.)
	  Decoder decoder = new Decoder(flags, new byte[len * 3 / 4]);

	  if (!decoder.process(input, offset, len, true))
	  {
		 throw new IllegalArgumentException("bad base-64");
	  }

	  // Maybe we got lucky and allocated exactly enough output space.
	  if (decoder.op == decoder.output.length)
	  {
		 return decoder.output;
	  }

	  // Need to shorten the array, so allocate a new one of the
	  // right size and copy.
	  byte[] temp = new byte[decoder.op];
	  System.arraycopy(decoder.output, 0, temp, 0, decoder.op);
	  return temp;
   }

   /** package */
   static class Decoder extends Coder
   {
	  /***
	   * Lookup table for turning bytes into their position in the UtiBase64
	   * alphabet.
	   */
	  private static final int DECODE[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,
			23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, };

	  /***
	   * Decode lookup table for the "web safe" variant (RFC 3548 sec. 4) where
	   * - and _ replace + and /.
	   */
	  private static final int DECODE_WEBSAFE[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
			21, 22, 23, 24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, };

	  /*** Non-data values in the DECODE arrays. */
	  private static final int SKIP = -1;
	  private static final int EQUALS = -2;

	  /***
	   * States 0-3 are reading through the next input tuple. State 4 is having
	   * read one '=' and expecting exactly one more. State 5 is expecting no
	   * more data or padding characters in the input. State 6 is the error
	   * state; an error has been detected in the input and no future input can
	   * "fix" it.
	   */
	  private int state; // state number (0 to 6)
	  private int value;

	  final private int[] alphabet;

	  public Decoder(int flags, byte[] output)
	  {
		 this.output = output;

		 alphabet = ((flags & URL_SAFE) == 0) ? DECODE : DECODE_WEBSAFE;
		 state = 0;
		 value = 0;
	  }

	  /***
	   * @return an overestimate for the number of bytes {@code len} bytes could
	   *         decode to.
	   */
	  public int maxOutputSize(int len)
	  {
		 return len * 3 / 4 + 10;
	  }

	  /***
	   * Decode another block of input data.
	   * 
	   * @return true if the state machine is still healthy. false if bad
	   *         base-64 data has been detected in the input stream.
	   */
	  public boolean process(byte[] input, int offset, int len, boolean finish)
	  {
		 if (this.state == 6)
			return false;

		 int p = offset;
		 len += offset;

		 // Using local variables makes the decoder about 12%
		 // faster than if we manipulate the member variables in
		 // the loop. (Even alphabet makes a measurable
		 // difference, which is somewhat surprising to me since
		 // the member variable is final.)
		 int state = this.state;
		 int value = this.value;
		 int op = 0;
		 final byte[] output = this.output;
		 final int[] alphabet = this.alphabet;

		 while (p < len)
		 {
			// Try the fast path: we're starting a new tuple and the
			// next four bytes of the input stream are all data
			// bytes. This corresponds to going through states
			// 0-1-2-3-0. We expect to use this method for most of
			// the data.
			//
			// If any of the next four bytes of input are non-data
			// (whitespace, etc.), value will end up negative. (All
			// the non-data values in decode are small negative
			// numbers, so shifting any of them up and or'ing them
			// together will result in a value with its top bit set.)
			//
			// You can remove this whole block and the output should
			// be the same, just slower.
			if (state == 0)
			{
			   while (p + 4 <= len
					 && (value = ((alphabet[input[p] & 0xff] << 18) | (alphabet[input[p + 1] & 0xff] << 12) | (alphabet[input[p + 2] & 0xff] << 6) | (alphabet[input[p + 3] & 0xff]))) >= 0)
			   {
				  output[op + 2] = (byte) value;
				  output[op + 1] = (byte) (value >> 8);
				  output[op] = (byte) (value >> 16);
				  op += 3;
				  p += 4;
			   }
			   if (p >= len)
				  break;
			}

			// The fast path isn't available -- either we've read a
			// partial tuple, or the next four input bytes aren't all
			// data, or whatever. Fall back to the slower state
			// machine implementation.

			int d = alphabet[input[p++] & 0xff];

			switch (state)
			{
			   case 0:
				  if (d >= 0)
				  {
					 value = d;
					 ++state;
				  }
				  else if (d != SKIP)
				  {
					 this.state = 6;
					 return false;
				  }
				  break;

			   case 1:
				  if (d >= 0)
				  {
					 value = (value << 6) | d;
					 ++state;
				  }
				  else if (d != SKIP)
				  {
					 this.state = 6;
					 return false;
				  }
				  break;

			   case 2:
				  if (d >= 0)
				  {
					 value = (value << 6) | d;
					 ++state;
				  }
				  else if (d == EQUALS)
				  {
					 // Emit the last (partial) output tuple;
					 // expect exactly one more padding character.
					 output[op++] = (byte) (value >> 4);
					 state = 4;
				  }
				  else if (d != SKIP)
				  {
					 this.state = 6;
					 return false;
				  }
				  break;

			   case 3:
				  if (d >= 0)
				  {
					 // Emit the output triple and return to state 0.
					 value = (value << 6) | d;
					 output[op + 2] = (byte) value;
					 output[op + 1] = (byte) (value >> 8);
					 output[op] = (byte) (value >> 16);
					 op += 3;
					 state = 0;
				  }
				  else if (d == EQUALS)
				  {
					 // Emit the last (partial) output tuple;
					 // expect no further data or padding characters.
					 output[op + 1] = (byte) (value >> 2);
					 output[op] = (byte) (value >> 10);
					 op += 2;
					 state = 5;
				  }
				  else if (d != SKIP)
				  {
					 this.state = 6;
					 return false;
				  }
				  break;

			   case 4:
				  if (d == EQUALS)
				  {
					 ++state;
				  }
				  else if (d != SKIP)
				  {
					 this.state = 6;
					 return false;
				  }
				  break;

			   case 5:
				  if (d != SKIP)
				  {
					 this.state = 6;
					 return false;
				  }
				  break;
			}
		 }

		 if (!finish)
		 {
			// We're out of input, but a future call could provide
			// more.
			this.state = state;
			this.value = value;
			this.op = op;
			return true;
		 }

		 // Done reading input. Now figure out where we are left in
		 // the state machine and finish up.

		 switch (state)
		 {
			case 0:
			   // Output length is a multiple of three. Fine.
			   break;
			case 1:
			   // Read one extra input byte, which isn't enough to
			   // make another output byte. Illegal.
			   this.state = 6;
			   return false;
			case 2:
			   // Read two extra input bytes, enough to emit 1 more
			   // output byte. Fine.
			   output[op++] = (byte) (value >> 4);
			   break;
			case 3:
			   // Read three extra input bytes, enough to emit 2 more
			   // output bytes. Fine.
			   output[op++] = (byte) (value >> 10);
			   output[op++] = (byte) (value >> 2);
			   break;
			case 4:
			   // Read one padding '=' when we expected 2. Illegal.
			   this.state = 6;
			   return false;
			case 5:
			   // Read all the padding '='s we expected and no more.
			   // Fine.
			   break;
		 }

		 this.state = state;
		 this.op = op;
		 return true;
	  }
   }

   // --------------------------------------------------------
   // encoding
   // --------------------------------------------------------

   /***
    * UtiBase64-encode the given data and return a newly allocated String with
    * the result.
    * 
    * @param input
    *           the data to encode
    * @param flags
    *           controls certain features of the encoded output. Passing
    *           {@code DEFAULT} results in output that adheres to RFC 2045.
    */
   public static String encodeToString(byte[] input, int flags)
   {
	  try
	  {
		 return new String(encode(input, flags), "US-ASCII");
	  }
	  catch (UnsupportedEncodingException e)
	  {
		 // US-ASCII is guaranteed to be available.
		 throw new AssertionError(e);
	  }
   }
   
   /***
    * UtiBase64-encode the given data and return a newly allocated String with
    * the result.
    * 
    * @param input
    *           the data to encode
    * @param offset
    *           the position within the input array at which to start
    * @param len
    *           the number of bytes of input to encode
    * @param flags
    *           controls certain features of the encoded output. Passing
    *           {@code DEFAULT} results in output that adheres to RFC 2045.
    */
   public static String encodeToString(byte[] input, int offset, int len, int flags)
   {
	  try
	  {
		 return new String(encode(input, offset, len, flags), "US-ASCII");
	  }
	  catch (UnsupportedEncodingException e)
	  {
		 // US-ASCII is guaranteed to be available.
		 throw new AssertionError(e);
	  }
   }

   /***
    * UtiBase64-encode the given data and return a newly allocated byte[] with
    * the result.
    * 
    * @param input
    *           the data to encode
    * @param flags
    *           controls certain features of the encoded output. Passing
    *           {@code DEFAULT} results in output that adheres to RFC 2045.
    */
   public static byte[] encode(byte[] input, int flags)
   {
	  return encode(input, 0, input.length, flags);
   }

   /***
    * UtiBase64-encode the given data and return a newly allocated byte[] with
    * the result.
    * 
    * @param input
    *           the data to encode
    * @param offset
    *           the position within the input array at which to start
    * @param len
    *           the number of bytes of input to encode
    * @param flags
    *           controls certain features of the encoded output. Passing
    *           {@code DEFAULT} results in output that adheres to RFC 2045.
    */
   public static byte[] encode(byte[] input, int offset, int len, int flags)
   {
	  Encoder encoder = new Encoder(flags, null);

	  // Compute the exact length of the array we will produce.
	  int output_len = len / 3 * 4;

	  // Account for the tail of the data and the padding bytes, if any.
	  if (encoder.do_padding)
	  {
		 if (len % 3 > 0)
		 {
			output_len += 4;
		 }
	  }
	  else
	  {
		 switch (len % 3)
		 {
			case 0:
			   break;
			case 1:
			   output_len += 2;
			   break;
			case 2:
			   output_len += 3;
			   break;
		 }
	  }

	  // Account for the newlines, if any.
	  if (encoder.do_newline && len > 0)
	  {
		 output_len += (((len - 1) / (3 * Encoder.LINE_GROUPS)) + 1) * (encoder.do_cr ? 2 : 1);
	  }

	  encoder.output = new byte[output_len];
	  encoder.process(input, offset, len, true);

	  assert encoder.op == output_len;

	  return encoder.output;
   }

   /** package */
   static class Encoder extends Coder
   {
	  /***
	   * Emit a new line every this many output tuples. Corresponds to a
	   * 76-character line length (the maximum allowable according to <a
	   * href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>).
	   */
	  public static final int LINE_GROUPS = 19;

	  /***
	   * Lookup table for turning UtiBase64 alphabet positions (6 bits) into
	   * output bytes.
	   */
	  private static final byte ENCODE[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e',
			'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/', };

	  /***
	   * Lookup table for turning UtiBase64 alphabet positions (6 bits) into
	   * output bytes.
	   */
	  private static final byte ENCODE_WEBSAFE[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c',
			'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_', };

	  final private byte[] tail;
	  /** package */
	  int tailLen;
	  private int count;

	  final public boolean do_padding;
	  final public boolean do_newline;
	  final public boolean do_cr;
	  final private byte[] alphabet;

	  public Encoder(int flags, byte[] output)
	  {
		 this.output = output;

		 do_padding = (flags & NO_PADDING) == 0;
		 do_newline = (flags & NO_WRAP) == 0;
		 do_cr = (flags & CRLF) != 0;
		 alphabet = ((flags & URL_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE;

		 tail = new byte[2];
		 tailLen = 0;

		 count = do_newline ? LINE_GROUPS : -1;
	  }

	  /***
	   * @return an overestimate for the number of bytes {@code len} bytes could
	   *         encode to.
	   */
	  public int maxOutputSize(int len)
	  {
		 return len * 8 / 5 + 10;
	  }

	  public boolean process(byte[] input, int offset, int len, boolean finish)
	  {
		 // Using local variables makes the encoder about 9% faster.
		 final byte[] alphabet = this.alphabet;
		 final byte[] output = this.output;
		 int op = 0;
		 int count = this.count;

		 int p = offset;
		 len += offset;
		 int v = -1;

		 // First we need to concatenate the tail of the previous call
		 // with any input bytes available now and see if we can empty
		 // the tail.

		 switch (tailLen)
		 {
			case 0:
			   // There was no tail.
			   break;

			case 1:
			   if (p + 2 <= len)
			   {
				  // A 1-byte tail with at least 2 bytes of
				  // input available now.
				  v = ((tail[0] & 0xff) << 16) | ((input[p++] & 0xff) << 8) | (input[p++] & 0xff);
				  tailLen = 0;
			   }
			   ;
			   break;

			case 2:
			   if (p + 1 <= len)
			   {
				  // A 2-byte tail with at least 1 byte of input.
				  v = ((tail[0] & 0xff) << 16) | ((tail[1] & 0xff) << 8) | (input[p++] & 0xff);
				  tailLen = 0;
			   }
			   break;
		 }

		 if (v != -1)
		 {
			output[op++] = alphabet[(v >> 18) & 0x3f];
			output[op++] = alphabet[(v >> 12) & 0x3f];
			output[op++] = alphabet[(v >> 6) & 0x3f];
			output[op++] = alphabet[v & 0x3f];
			if (--count == 0)
			{
			   if (do_cr)
				  output[op++] = '\r';
			   output[op++] = '\n';
			   count = LINE_GROUPS;
			}
		 }

		 // At this point either there is no tail, or there are fewer
		 // than 3 bytes of input available.

		 // The main loop, turning 3 input bytes into 4 output bytes on
		 // each iteration.
		 while (p + 3 <= len)
		 {
			v = ((input[p] & 0xff) << 16) | ((input[p + 1] & 0xff) << 8) | (input[p + 2] & 0xff);
			output[op] = alphabet[(v >> 18) & 0x3f];
			output[op + 1] = alphabet[(v >> 12) & 0x3f];
			output[op + 2] = alphabet[(v >> 6) & 0x3f];
			output[op + 3] = alphabet[v & 0x3f];
			p += 3;
			op += 4;
			if (--count == 0)
			{
			   if (do_cr)
				  output[op++] = '\r';
			   output[op++] = '\n';
			   count = LINE_GROUPS;
			}
		 }

		 if (finish)
		 {
			// Finish up the tail of the input. Note that we need to
			// consume any bytes in tail before any bytes
			// remaining in input; there should be at most two bytes
			// total.

			if (p - tailLen == len - 1)
			{
			   int t = 0;
			   v = ((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 4;
			   tailLen -= t;
			   output[op++] = alphabet[(v >> 6) & 0x3f];
			   output[op++] = alphabet[v & 0x3f];
			   if (do_padding)
			   {
				  output[op++] = '=';
				  output[op++] = '=';
			   }
			   if (do_newline)
			   {
				  if (do_cr)
					 output[op++] = '\r';
				  output[op++] = '\n';
			   }
			}
			else if (p - tailLen == len - 2)
			{
			   int t = 0;
			   v = (((tailLen > 1 ? tail[t++] : input[p++]) & 0xff) << 10) | (((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 2);
			   tailLen -= t;
			   output[op++] = alphabet[(v >> 12) & 0x3f];
			   output[op++] = alphabet[(v >> 6) & 0x3f];
			   output[op++] = alphabet[v & 0x3f];
			   if (do_padding)
			   {
				  output[op++] = '=';
			   }
			   if (do_newline)
			   {
				  if (do_cr)
					 output[op++] = '\r';
				  output[op++] = '\n';
			   }
			}
			else if (do_newline && op > 0 && count != LINE_GROUPS)
			{
			   if (do_cr)
				  output[op++] = '\r';
			   output[op++] = '\n';
			}

			assert tailLen == 0;
			assert p == len;
		 }
		 else
		 {
			// Save the leftovers in tail to be consumed on the next
			// call to encodeInternal.

			if (p == len - 1)
			{
			   tail[tailLen++] = input[p];
			}
			else if (p == len - 2)
			{
			   tail[tailLen++] = input[p];
			   tail[tailLen++] = input[p + 1];
			}
		 }

		 this.op = op;
		 this.count = count;

		 return true;
	  }
   }

   private UtiBase64()
   {
   } // don't instantiate
}
